Systems, methods and devices for the management of heat removal within a compression and/or expansion device or system

ABSTRACT

Systems, methods and devices for optimizing heat transfer within a device or system used to compress and/or expand a gas, such as air, are described herein. In some embodiments, a compressed air device and/or system can include an actuator such as a hydraulic actuator that can be used to compress a gas within a pressure vessel. An actuator can be actuated to move a liquid into a pressure vessel such that the liquid compresses gas within the pressure vessel. In such a compressor/expander device or system, during the compression and/or expansion process, heat can be transferred to the liquid used to compress the air. The compressor/expander device or system can include a liquid purge system that can be used to remove at least a portion of the liquid to which the heat energy has been transferred such that the liquid can be cooled and then recycled within the system.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 61/432,331, entitled “Systems, Methods andDevices for the Management of Heat Removal within a Compression and/orExpansion Device or System,” filed on Jan. 13, 2011, the disclosure ofwhich is hereby incorporated herein in its entirety.

BACKGROUND

The invention relates generally to systems, devices and methods for thecompression and/or expansion of a gas, such as air, and particularly toa system, device and method for optimizing heat transfer during thecompression and/or expansion of a gas.

Some known devices, methods and systems used to compress and/or expand agas, such as air, and/or to pressurize and/or pump a liquid, such aswater, can be used, for example, within a compressed air energy storagesystem. In some compressed air devices and systems, a hydraulic actuatorcan be used to move or compress air within a pressure vessel. Forexample, an actuator can move a liquid within a pressure vessel suchthat the liquid compresses air in the pressure vessel.

Such known devices and systems used to compress and/or expand a gasand/or to pressurize and/or pump a liquid can change the temperature ofthe gas during, for example, a compression or expansion process. Forexample, compressing a gas can convert heat energy from its latent forminto its sensible form, thereby increasing the temperature of the gas.Various heat transfer mechanisms can be used to remove heat energy fromthe gas being compressed during the compression process. In some knowndevices and systems, heat energy in the gas being compressed within apressure vessel can also be transferred to the liquid used to compressthe gas.

Thus, there is a need to improve and/or optimize the heat transferdevices and methods used to transfer heat during a compression and/orexpansion process within such devices and systems used to compressand/or expand a gas.

SUMMARY OF THE INVENTION

Systems, methods and devices for optimizing heat transfer within adevice or system used to compress and/or expand a gas, such as air, aredescribed herein. In some embodiments, a compressed air device and/orsystem can include an actuator such as a hydraulic actuator that can beused to compress a gas within a pressure vessel. An actuator can beactuated to move a liquid into a pressure vessel such that the liquidcompresses gas within the cylinder or pressure vessel. In such acompressor/expander device or system, during the compression and/orexpansion process, heat can be transferred to the liquid used tocompress the air. The compressor and/or expander device or system caninclude a liquid purge system that can be used to remove at least aportion of the liquid to which the heat energy has been transferred suchthat the liquid can be cooled and then recycled within the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a compression and/or expansionsystem according to an embodiment.

FIG. 2 is a schematic illustration of a compression and/or expansiondevice according to an embodiment, showing a first time period of acompression cycle.

FIG. 3 is a schematic illustration of the compression and/or expansiondevice of FIG. 2 showing a second time period of a compression cycle.

FIG. 4 is a schematic illustration of the compression and/or expansiondevice of FIG. 2 showing a third time period of a compression cycle.

FIG. 5 is a schematic illustration of the compression and/or expansiondevice of FIG. 2 showing a fourth time period of a compression cycle.

FIG. 6 is a schematic illustration of the compression and/or expansiondevice of FIG. 2 showing a fifth time period of a compression cycle.

FIG. 7 is a schematic illustration of a compression and/or expansiondevice according to another embodiment.

FIG. 8 is a schematic illustration of a compression and/or expansiondevice, according to another embodiment.

DETAILED DESCRIPTION

Systems, methods and devices used to compress and/or expand a gas, suchas air, and/or to pressurize and/or pump a liquid, such as water, aredescribed herein. Such devices and systems can be used, for example,within a compressed air energy storage (CAES) system. In somecompression and/or expansion devices and systems, a hydraulic actuatorcan be used to move or compress a gas within a pressure vessel. Forexample, an actuator can move a liquid within a pressure vessel suchthat the liquid compresses the gas in the pressure vessel. Suchcompression devices and systems are described in U.S. Provisional App.No. 61/216,942 and U.S. Patent Publication Nos. 2011/0061741,2011/0061836 and 2011/0062166, each entitled “Compressor and/or ExpanderDevice” (collectively referred to as “the Compressor and/or ExpanderDevice applications”), incorporated herein by reference in theirentirety. The Compressor and/or Expander Device applications describe aCAES system that can include multiple stages of compression and/orexpansion. Other examples of devices and systems for expanding and/orcompressing as gas are described in U.S. patent application Ser. No.12/977,724 to Ingersoll et al. (“the Ingersoll I application”), entitled“System and Methods for Optimizing Efficiency of a HydraulicallyActuated System,” and U.S. patent application Ser. No. 12/977,679 toIngersoll et al. (“the Ingersoll II application”), entitled “Methods andDevices for Optimizing Heat Transfer Within a Compression and ExpansionDevice,” the disclosures of which are incorporated herein by referencein their entirety.

In some compression and/or expansion devices and systems, a piston canbe movably disposed within a cylinder or pressure vessel and actuated tocompress air within the cylinder or pressure vessel. Such a device caninclude a single-acting piston configured to compress gas when moved ina single direction, or a double-acting piston configured to compress gaswhen moved in either direction. Examples of such compressed air devicesand systems are described in U.S. Patent App. No. 61/420,505 toIngersoll et al. (“the Ingersoll III application”), entitled “Compressorand/or Expander Device with Rolling Piston Seal,” the disclosure ofwhich is incorporated herein by reference in its entirety.

In some embodiments, the devices and systems described herein can beconfigured for use only as a compressor. For example, in someembodiments, a compressor device described herein can be used as acompressor in a natural gas pipeline, a natural gas storage compressor,or any other industrial application that requires compression of a gas.In another example, a compressor device described herein can be used forcompressing carbon dioxide. For example, carbon dioxide can becompressed in a process for use in enhanced oil recovery or for use incarbon sequestration.

In some embodiments, the devices and systems described herein can beconfigured for use only as an expansion device. For example, anexpansion device as described herein can be used to generateelectricity. In some embodiments, an expansion device as describedherein can be used in a natural gas transmission and distributionsystem. For example, at the intersection of a high pressure (e.g., 500psi) transmission system and a low pressure (e.g., 50 psi) distributionsystem, energy can be released where the pressure is stepped down fromthe high pressure to a low pressure. An expansion device as describedherein can use the pressure drop to generate electricity. In otherembodiments, an expansion device as described herein can be used inother gas systems to harness the energy from high to low pressureregulation.

In some embodiments, a compression and/or expansion device (alsoreferred to herein as compressor/expander device) as described hereincan be used in an air separation unit. In one example application, in anair separator, a compression and/or expansion device can be used in aprocess to liquefy a gas. For example, air can be compressed until itliquefies and the various constituents of the air can be separated basedon their differing boiling points. In another example application, acompression and/or expansion device can be used in an air separatorco-located within a steel mill where oxygen separated from the othercomponents of air is added to a blast furnace to increase the burntemperature.

A compression and/or expansion system can have a variety of differentconfigurations and can include one or more actuators that are used tocompress/expand a gas (e.g. air), within a compression/expansion device.In some embodiments, an actuator can include one or more pump systems,such as for example, one or more hydraulic pumps and/or one or morepneumatic pumps that can be use to move one or more fluids within thesystem between various water pumps and pressure vessels. As used herein,“fluid” can mean a liquid, gas, vapor, suspension, aerosol, or anycombination thereof. The Compressor and/or Expander Device applicationsincorporated by reference above describe various energy compression andexpansion systems in which the systems and methods described herein canbe employed.

As described herein, devices and systems used to compress and/or expanda gas, such as air, and/or to pressurize and/or pump a liquid, such aswater, can release heat during, for example, a compression processand/or can absorb heat during, for example, an expansion process. Thedevices and systems described herein can include one or more heattransfer mechanisms to remove and/or add heat during the compressionand/or expansion processes. In some embodiments, a heat transfer elementcan be used as described, for example, in the Compressor and/or ExpanderDevice applications and/or the Ingersoll II application incorporated byreference above. During an expansion process in a CAES system, whencompressed air is released from a storage structure and expanded throughthe compressor/expander system, heat from a source can be added to theair to increase the power generated during the expansion process. Insome embodiments, the source of heat can be at a relatively lowtemperature (e.g., between, for example, about 10° C. and about 50° C.).

In some embodiments, a heat transfer element can be positioned withinthe interior of a pressure vessel of a compressor/expander device toincrease the amount of surface area within the pressure vessel that isin direct or indirect contact with gas, which can improve heat transfer.The heat transfer element may be configured to minimize the distancethat heat must travel through the air in order to reach the heattransfer element, such as a maximum distance of ⅛″, and other distances.The heat transfer element can provide for an increased heat transferarea both with gas that is being compressed and with gas that is beingexpanded (through a gas/liquid interface area and/or gas/heat transferelement interface), while allowing the exterior structure and overallshape and size of a pressure vessel to be optimized for otherconsiderations, such as, for example, pressure limits and/or shippingsize limitations. In some embodiments, the heat transfer element can bea thermal capacitor that absorbs and holds heat released from a gas thatis being compressed, and then releases the heat to a gas or a liquid ata later time. In some embodiments, the heat transfer element can be aheat transferring device that absorbs heat from a gas that is beingcompressed, and then facilitates the transfer of the heat outside of thepressure vessel.

In some embodiments, heat energy can be removed from a gas duringcompression via a liquid that is present in one or more pressure vesselsof a compressor/expander device to maintain the gas that is beingcompressed at a relatively constant temperature. The heat energy can betransferred from the gas to the liquid and/or the compressor and/orexpander device to a heat transfer element disposed within the pressurevessel. After gas is provided to the compressor/expander device, heatenergy is removed from the gas, i.e. the gas is kept cooler as it iscompressed than would be the case without the heat transfer element, andmay be done to an extent that the temperature of the gas remainsrelatively constant. The temperature of the gas can be maintained, forexample, at about 5° C., 10° C., 20° C., 30° C. or other temperaturesthat may be desirable, until discharged to, for example, a compressedgas storage structure or a subsequent compression stage. The gas storedin the storage structure may be heated (or cooled) naturally throughconductive and/or convective heat transfer if the storage structure isnaturally at a higher (or lower) temperature. For example, in somecases, the storage structure may be an underground structure, such as asalt cavern constructed in a salt dome that is used for storing thecompressed gas. In some embodiments, the heat transfer element can bedesigned such that the temperature of the gas does not remain relativelyconstant, but instead increases a relatively small amount, for example,5° C., 10° C., 20° C., 30° C.

As discussed above, heat may be added to the gas during an expansionprocess. For example, heat can be added to the gas at each of the stagesof a multi-stage compression/expansion system to hold gas temperaturesat a substantially constant temperature, such as at about 35° C., orother temperatures, during the entire expansion process. The overalltemperature change of gas during expansion may be limited by arelatively large amount of gas that expands in a relatively small volumeof a pressure vessel, and that is in contact with substantial heattransfer surfaces.

As discussed above, heat can be transferred from and/or to gas that iscompressed and/or expanded by liquid (e.g., water) within a pressurevessel. A gas/liquid or gas/heat element interface may move and/orchange shape during a compression and/or expansion process in a pressurevessel. This movement and/or shape change may provide acompressor/expander device with a heat transfer surface that canaccommodate the changing shape of the internal areas of a pressurevessel in which compression and/or expansion occurs. In someembodiments, the liquid may allow the volume of gas remaining in apressure vessel after compression to be nearly eliminated or completelyeliminated (i.e., zero clearance volume).

A liquid (such as water) can have a relatively high thermal capacity ascompared to a gas (such as air) such that a transfer of an amount ofheat energy from the gas to the liquid avoids a significant increase inthe temperature of the gas, but incurs only a modest increase in thetemperature of the liquid. This allows buffering of the system fromsubstantial temperature changes. Said another way, this relationshipcreates a system that is resistant to substantial temperature changes.Heat that is transferred between the gas and liquid, or components ofthe vessel itself, may be moved from or to the pressure vessel throughone or more processes. In some embodiments, heat can be moved in or outof the pressure vessel using mass transfer of the compression liquiditself. In other embodiments, heat can be moved in or out of thepressure vessel using heat exchange methods that transfer heat in or outof the compression liquid without removing the compression liquid fromthe pressure vessel. Such heat exchangers can be in thermal contact withthe compression liquid, components of the pressure vessel, a heattransfer element, or any combination thereof. Furthermore, heatexchangers may also use mass transfer to move heat in or out of thepressure vessel. One type of heat exchanger that can be used toaccomplish this heat transfer is a heat pipe as described in theCompressor and/or Expander Device applications and the Ingersoll Iapplication incorporated by reference above. Thus, the liquid within apressure vessel can be used to transfer heat from gas that is compressed(or to gas that is expanded) and can also act in combination with a heatexchanger to transfer heat to an external environment (or from anexternal environment).

In some embodiments, heat can be transferred from a gas (such as air)that is compressed in a pressure vessel to increase the efficiency ofthe compression process. Heat can be transferred from the gas to aliquid, and/or from the gas to a heat transfer element within thecompression vessel, and/or from the compression liquid while it isinside or outside of the pressure vessel. The amount of heat transferredfrom an amount of gas being compressed can depend on the rate of heattransfer from the gas and on the time over which the heat transfer takesplace, i.e. over the cycle time during which the gas compression takesplace. Thus, for a given rate of heat transfer that can be achieved by asystem, the more slowly the system is operated (i.e., the longer thecompression cycle times), the more closely the compression cycle canapproach isothermal compression. However, slower compression cycle timesalso correlate to lower gas volumetric and/or mass flow rates. In thecontext of a CAES system, this equates to lower energy storage rates,equivalently known as lower power. Conversely, in a gas expansionprocess, the more slowly the system is operated, the more heat energycan be transferred to the expanding gas (for a given heat transfer rate)and the more closely the expansion cycle can approach isothermalexpansion, which may correspond to more efficient consumption of airmass relative to energy extracted/converted. However, in the context ofa CAES system, the resulting lower expanding gas flow rate may equate tolower power production.

The use of a liquid (e.g. water) as a medium through which heat passes(directly through contact between the gas and liquid, or indirectlythrough an intermediary material) during compression and/or expansionmay allow for continuous cooling or heating at enhanced heat transferrates and may provide a mechanism by which heat may be moved in and/orout of the pressure vessel. That is, during compression, the liquid mayreceive heat from gas that is being compressed and transfer this heatfrom the pressure vessel to the external environment continuously, bothwhile gas is being compressed and while gas is being received by thepressure vessel for later compression. Similarly, heat addition mayoccur when a compressor/expander device is operating in an expansionmode both during expansion, and as expanded gas is passed from thepressure vessel.

The heat energy transferred from the gas to the liquid can be removedfrom the pressure vessel by transferring the heat energy from the liquidto or through some other medium to the surrounding environment or otherlocation outside the pressure vessel. Alternatively, or in addition, thewater itself can be transferred out of the pressure vessel (along withthe stored heat energy). Thus, in some embodiments, a compression and/orexpansion device can include a liquid purge system that can remove someor all of the liquid used to receive heat energy from a gas compressedwithin a pressure vessel (or liquid used to provide heat energy to a gasexpanded within the pressure vessel). For example, in such a compressionand/or expansion device, heat energy can be transferred from the gas tothe liquid, and a volume of the heated liquid can then be purged fromthe pressure vessel to a location where the heated liquid can be cooled.Once cooled, the liquid can be cycled back into the system for use incompressing the gas within a pressure vessel. In some embodiments, allof the liquid used to compress the gas within a pressure vessel can bepurged from the pressure vessel. In some embodiments, the purged liquidcan be discharged to the next stage in a multi-stagecompression/expansion system.

In some embodiments, only a predetermined portion or volume of theliquid used to compress the gas within a pressure vessel is purged.Depending on, for example, the geometry of the system, the rate of heattransfer, and/or the cycle time, there may be a significant temperaturegradient in the liquid contained in the pressure vessel. For example, ifa column of water is exposed at its surface to the gas duringcompression (e.g., if the water column, driven by a mechanical piston,is used to compress the gas) heat energy transferred though the surfaceand into the water column will create a temperature gradient in whichthe surface is at the highest temperature and the temperature decreasesthrough the column with distance from the surface. The profile of thegradient may be such that a large portion of the total heat energytransferred from the gas to the liquid is contained in a relatively thinlayer of the fluid adjacent the surface. Thus, it may be desirable toremove or evacuate only a predetermined portion or volume of liquid inthat layer, closest to the gas being compressed. The volume of liquid tobe purged can be selected so as to remove a desired amount of heatenergy from the compression and/or expansion device or system at anacceptable cost in operating energy and/or equipment cost, and with anacceptable impact on cycle time, to purge that volume of liquid from thedevice and to replace it. By evacuating only a portion of the volume ofliquid used to compress the gas, the cycle time of the compressionand/or expansion process can be reduced. Additionally, with shortercycle times, less actuating power may be needed, and therefore, thecompression and/or expansion device can include smaller and/or lessexpensive actuators to pump the compression liquid within the system.

Thus, in some embodiments, the stroke of the compression cycle can betailored to the needs of the particular system or facility, trading offenergy storage rates against operating efficiency. For example, in agiven CAES system, it may be desirable to operate with a stroke time forthe compression cycle of, for example, 3 seconds to generate a maximumenergy storage rate (limited by operating constraints such as actuatorpower). Alternatively, if a lower energy storage rate is acceptable, itmay be desirable to operate at higher energy efficiency, with acompression cycle of, for example, 6.5 seconds.

In some embodiments, it may be desirable for the temperature of thecompression/heat transfer liquid (e.g., water) to approach thetemperature of the gas (e.g., air) as closely as possible during acompression cycle so as to not degrade waste heat. For example, ifduring a compression cycle the gas increases in temperature by 3degrees, it may be desirable for the liquid at the top layer (e.g.,closes to the gas) to increase, for example, 2 degrees. This top layerof liquid can be transferred out of the pressure vessel at the end ofthe compression cycle, and the system can be replenished with a newlayer of liquid. This can provide a system with entropy minimization.

In some embodiments, for example, within a multi-stage CAES system, aliquid purge system can be included at each stage in the system. In someembodiments, only one stage may include a liquid purge system. Forexample, a first stage of a CAES system may include a liquid purgesystem, and the remaining stages may include heat exchangers or othermethods to remove heat generated during a compression cycle. In someembodiments, more than one stage, but not all stages, can include aliquid purge system.

In some embodiments, a compression and/or expansion device can include aliquid purge system and also include one or more heat transfer elements(e.g., a heat transfer element as described in the Ingersoll IIapplication incorporated by reference above) disposed within thepressure vessel. In such an embodiment, some of the heat energy can betransferred to the heat transfer element(s), and some of the heat energycan be transferred to the compression liquid. In some embodiments, thecompression and/or expansion device can include a liquid purge systemand not include a heat transfer element.

FIG. 1 schematically illustrates a portion of a compression and/orexpansion device (also referred to herein as “compression/expansiondevice”) according to an embodiment. A compression/expansion device 100can include one or more pressure vessels 120 (also referred to herein as“cylinder”) having a working chamber 126, an actuator 122 by which thevolume of working chamber 126, and/or the portion of the volume of theworking chamber 126 that can be occupied by gas, can be changed(decreased to compress the gas, increased to expand the gas), and one ormore heat transfer elements 124 disposed within the working chamber 126.The compression/expansion device 100 also includes a liquid purge system138 coupled to the working chamber 126 and the actuator 122. Thecompression/expansion device 100 can be used, for example, to compressor expand a gas, such as air, within the working chamber 126. Thecompression/expansion device 100 can be used, for example, in a CAESsystem.

The compression/expansion device 100 can include a gas inlet/outletconduit 128 (also referred to as “gas inlet/outlet”), a first liquidinlet/outlet conduit (also referred to as “first liquid inlet/outlet”)130 and a second liquid inlet/outlet conduit (also referred to as“second liquid inlet/outlet”) 132, each in fluid communication with theworking chamber 126. In alternative embodiments, thecompression/expansion device 100 can include more or less inlet/outletconduits. For example, in some embodiments, two gas inlet/outletconduits can be included. In some embodiments, a separate gas inletconduit and gas outlet conduit and/or a separate liquid inlet and liquidoutlet conduit can be included, each in fluid communication with theworking chamber 126.

The working chamber 126 can contain at various time periods during acompression and/or expansion cycle, a liquid (e.g., water) that can becommunicated to and from the working chamber 126 of the pressure vessel120 via the first liquid inlet/outlet 130 and/or the second liquidinlet/outlet 132, and/or a gas (e.g., air) that can be communicated toand from the working chamber 126 via the inlet/outlet 128. Thecompression/expansion device 100 can also include multiple valves (notshown in FIG. 1) coupled to the gas inlet/outlet 128, the first liquidinlet/outlet 130 and the second liquid inlet/outlet 132 and/or to thepressure vessel 120. The valves can be configured to operatively openand close the fluid communication to and from the working chamber 126.Examples of use of such valves are described in more detail in theCompressor and/or Expander Device applications incorporated by referenceabove.

The actuator 122 can be any suitable mechanism for selectively changingthe volume of the working chamber 126 and/or the portion of the volumeof the working chamber that can be occupied by gas. For example, theworking chamber 126 can be defined by a cylinder and the face of apiston (not shown in FIG. 1) disposed for reciprocal movement within thecylinder. Movement of the piston in one direction would reduce thevolume of the working chamber 126, thus compressing gas contained in theworking chamber 126, while movement of the piston in the other directionwould increase the volume of the working chamber 126, thus expanding gascontained in the working chamber 126. The actuator 122 can thus be thepiston and a suitable device for moving the piston within the cylinder,such as a pneumatic or hydraulic actuator such as, for example, thehydraulic actuators described in the Ingersoll I application.

In some embodiments, the working chamber 126 can have a fixed volume,i.e. a volume defined by a chamber with fixed boundaries, and theportion of the volume of the working chamber 126 that can be occupied bygas can be changed by introducing a liquid into, or removing a liquidfrom, the working chamber 126. Thus, the total volume of the workingchamber 126 can include a first portion containing a volume of liquid,and a second portion that can contain a volume of gas. In suchembodiments, the actuator 122 can be any suitable device for introducingliquid into, or removing liquid from, the working chamber 126, such as ahydraulic actuator that can move a liquid in and out of the workingchamber 126 via liquid inlet/outlet conduit 130. In such an embodiment,the actuator 122 can include a water pump (not shown) that drives ahydraulically driven piston (not shown) disposed within a housing (notshown) and can be driven with one or more hydraulic pumps (not shown) tomove a volume of liquid in and out of the working chamber 126. Anexample of such a hydraulic actuator is described in the Compressorand/or Expander Device applications incorporated by reference above.

In some embodiments, the working chamber can be configured to combinethe techniques described above, i.e. the working chamber can have avariable volume, e.g. using a cylinder and piston as described above,and the portion of the variable volume that can be occupied by gas canbe changed by introducing liquid into, or removing a liquid from, theworking chamber. In another embodiment, a constant volume of liquid canbe maintained in the variable volume working chamber throughout all, ora portion, of the compression cycle.

The gas inlet/outlet 128 can be coupled to a source of gas 134, such as,for example, a source of ambient air (at ambient pressure, orpre-pressurized by another compression system), and can also be coupledto a compressed gas storage structure 136 to which gas can betransferred after being compressed. The valves can be used to open andclose the fluid communication between the pressure vessel 120 and thesource of gas 134 and between the pressure vessel 120 and the storagestructure 136. The first liquid inlet/outlet 130 can be coupled to theactuator 122 and can be opened and closed via a valve to communicate avolume of liquid inside and/or out of the pressure vessel 120. Thesecond liquid inlet/outlet 132 can be coupled to the liquid purge system138 and opened via a valve to evacuate a volume of the liquid from thepressure vessel 120, as described in more detail below.

The heat transfer element 124 can be a variety of differentconfigurations, shapes, sizes, structures, etc. to provide a relativelyhigh surface area per unit volume or mass that can be in contact withthe gas (e.g., air) as it is being compressed or expanded within theworking chamber 126. In some embodiments, it may be desirable to includea heat transfer element 124 that can be formed with a material that canprovide high thermal conductivity in a transverse and a longitudinaldirection within the working chamber 126. The heat transfer element 124can be formed from one or more of a variety of different materials. Forexample, the heat transfer element 124 can be formed with metals (e.g.stainless steel), metal wires, hybrid wires, carbon fiber,nano-materials, and composite materials (e.g. carbon polymer compounds)which have anti-corrosion properties, are lighter weight, and are lessexpensive than some metallic materials.

The heat transfer element 124 can be disposed at various locationswithin the working chamber 126 so as to optimize the heat transferwithin the pressure vessel 120. For example, in some embodiments, theheat transfer element 124 can be disposed within the working chamber 126near an end portion of the working chamber 126 in a portion occupied bythe gas (e.g., air) near the end of a compression cycle. As the gas iscompressed during the compression cycle, the work done on the gas addsenergy to the gas. During the compression cycle heat energy iscontinuously transferred (primarily by conductive and/or convective,rather than radiant, heat transfer) to the heat transfer element 124.This transfer maintains the gas temperature at a lower value than wouldbe the case without the heat transfer element 124, and moderatelyincreases the temperature of the heat transfer element 124.

The actuator 122 can be, for example a hydraulic actuator that can movea liquid in and out of the working chamber 126 via the first liquidinlet/outlet 130. In such an embodiment, the actuator 122 can include awater pump (not shown) in which a piston can be driven with one or morehydraulic pumps (not shown) to move a volume of liquid in and out of theworking chamber 126. An example of such a hydraulic actuator isdescribed in the Compressor and/or Expander Device applications and theIngersoll I application. In some embodiments, the actuator 122 can becoupled to, for example, an electric motor/generator and/or ahydraulically driven actuator such as, for example, the hydraulicactuators described in the Ingersoll I application incorporated byreference above.

The liquid purge system 138 can include a pump (not shown) that can beactuated to move liquid from the working chamber 126 to a thermalmanagement facility 140. The pump can also be used to pump liquid fromthe thermal management facility 140 to the actuator 122. The thermalmanagement facility 140 can include, for example, a cooling tower or acontainment pond, where heated liquid removed from the working chamber126 can be cooled to a desired temperature. The cooled liquid can becycled back into the actuator 122 and used again in a compressionprocess as described in more detail below.

The thermal management facility 140 can also include a source of heatsuch as, for example, low grade or waste heat from an industrial plant,so that heat can be added to the liquid before it is cycled back intothe actuator 122 and used in an expansion process. In this manner, heatcan be added to the gas to increase the electricity generation from theexpansion process and/or increase the overall efficiency of theexpansion process. For example, heat can be added to the gas at each ofthe stages of a multi-stage compression/expansion system to maintain gastemperatures at a substantially constant temperature, such as at about35° C., or other temperatures, during the entire expansion process.

As described above, in some embodiments, the working chamber 126 cancontain a liquid. The actuator 122 can be used to change the portion ofthe working chamber 126 that is available to contain gas, by moving aliquid, such as water, into and out of the working chamber 126 such thatgas, such as air, within the working chamber 126 is compressed by theliquid. In such embodiments, depending on the rate at which the workingchamber 126 is filled with liquid, and the heat transfer properties ofthe heat transfer element 124, the gas and the heat transfer element 124will be relatively closer or farther from thermal equilibrium. Thus,during some or all of the compression cycle, the liquid in the workingchamber 126 can be caused to contact the heat transfer element 124 toreceive from the heat transfer element 124 heat energy it received fromthe compressed gas. Optionally, at the end of the compression cycle, anypressurized gas remaining in the working chamber 126 can be releasedfrom the working chamber 126 and transferred to the next step or stagein the compression process, or to a storage facility. Liquid can then bemoved into the working chamber 126 to substantially fill the volumepreviously occupied by gas that was moved from the working chamber 126after compression (e.g., by introducing more liquid and/or by reducingthe volume of the working chamber (e.g. by moving a piston)). The heatenergy stored in the heat transfer element 124 can then be transferred(again, by conductive and/or convective transfer) to the water in theworking chamber 126.

In one example use of the compression/expansion device 100, a firstquantity of gas having a first pressure can be introduced into theworking chamber 126 via the gas inlet/outlet 128. For example, a gassource 134 can be coupled to the gas inlet/outlet 128. The gas sourcecan supply, for example, ambient air. A valve or valves coupled to thegas inlet/outlet 128 can be opened to allow a quantity of gas (e.g.,air) to enter the working chamber 126. With the first quantity of gasdisposed within the working chamber 126, the valve coupled to the gasinlet/outlet 128 can be closed and optionally, a valve coupled to theliquid inlet/outlet 130 can be opened. The actuator 122 can then pump avolume (or quantity) of liquid (e.g., water) into the working chamber126 via the first liquid inlet/outlet 130. The volume of liquid can bepumped into the working chamber 126 such that it compresses the gaswithin the working chamber 126. The gas inlet/outlet 128 can be openedsuch that as the volume of liquid compresses the gas, the compressedgas, now at a second pressure greater than the first pressure, can exitthe working chamber 126 via the gas inlet/outlet 128 and be transferredto the storage structure 136 or to another desired location.

At the end of the compression cycle, a valve coupled to the secondliquid inlet/outlet 132 can be opened to allow a volume of liquid to beevacuated from the working chamber 126. As described above, heat energycan be transferred from the gas to the liquid and/or from the heattransfer element 124 to the liquid. Some or all of the volume of liquidcan then be evacuated or purged from the working chamber 126 via theliquid purge system 138 and transferred to the thermal managementfacility 140. If only a portion of the volume of liquid used to compressthe gas is evacuated via the liquid purge system 138, the remainingportion or volume of liquid can be moved back into the actuator 122 viathe first liquid inlet/outlet 130. Cooled liquid can be transferred fromthe thermal management facility 140 to the actuator 122 to replace thevolume of liquid that has been evacuated.

In alternative embodiments, the thermal management facility 140 cantransfer a volume of liquid to the actuator 122 via a separate pump,rather than the pump of the liquid purge system 138. For example, a pumpcan be provided between the thermal management facility 140 and theactuator 122. In such an embodiment, the liquid purge system 138 can becoupled directly to the thermal management facility 140 via a conduit,but may not be coupled directly to the actuator 122.

In another example use of the compression/expansion device 100, a valvecoupled to the second liquid inlet/outlet 132 can be opened to allow avolume of warmed liquid from the thermal management facility 140 to beintroduced into the working chamber 126. The valve coupled to the secondliquid inlet/outlet 132 can be closed and a valve or valves coupled tothe gas inlet/outlet 128 can be opened to allow a quantity of gas at afirst pressure (e.g. air) from the storage structure 136 to enter theworking chamber 126. As the gas enters the working chamber 126 itexpands and forces a volume (or quantity) of liquid (e.g., water) intothe actuator 122 via the first liquid inlet/outlet 130. This movement ofliquid into the actuator 122 can be used, for example, to generateelectricity.

At the end of the expansion cycle, a valve coupled to the gasinlet/outlet 128 can be opened to allow the expanded gas, now at asecond pressure less than the first pressure, to be evacuated from theworking chamber 126 to the next stage in a multi-stage expansion processor to the atmosphere. As described above, heat energy can be transferredfrom the liquid to the gas and/or from the heat transfer element 124 tothe gas. Some or all of the volume of cooled liquid can then beevacuated or purged from the working chamber 126 and/or actuator 122 andtransferred to the thermal management facility 140. Warmed liquid can betransferred from the thermal management facility 140 to the workingchamber 126 to replace the volume of liquid that has been evacuated.

FIGS. 2-6 illustrate a compression/expansion device according to anotherembodiment. A compression/expansion device 200 includes a pressurevessel 220, an actuator 222 coupled to the pressure vessel 220, and aliquid purge system 238 coupled to the pressure vessel 220 and theactuator 222. The compression/expansion device 200 can be used, forexample, to compress a gas, such as air, within the pressure vessel 220and/or to pressurize and/or pump a liquid, such as water. Thecompression/expansion device 200 can also be used in a compression andexpansion system such as a compressed air energy storage system. Thecompression/expansion device 200 described below refers to the use ofwater as the liquid and air as the gas for discussion purposes. Itshould be understood that in alternative embodiments, a different liquidand/or a different gas can be used.

Coupled to the pressure vessel 220 is a gas inlet/outlet conduit 228(also referred to a as “gas inlet/outlet”), a liquid inlet/outletconduit 230 (also referred to as “liquid inlet/outlet”) and a liquidoutlet conduit 232 (also referred to as “liquid outlet”), each in fluidcommunication with a working chamber 242 of the pressure vessel 220. Thepressure vessel 220 can contain within the working chamber 242 atvarious time periods during a compression and/or expansion cycle, afluid, such as a liquid (e.g., water) and/or a gas (e.g., air). Thefluid can be communicated to and from the working chamber 242 via theliquid inlet/outlet 230 or liquid outlet 232 for the liquid, or gasinlet/outlet 228 for the gas. The compression/expansion device 200 canalso include multiple valves 244 coupled to the gas inlet/outlet 228,liquid inlet/outlet 230 and liquid outlet 232 and/or to the pressurevessel 220. The valves 244 can be configured to operatively open andclose the fluid communication to and from the working chamber 242.Examples of use of such valves are described in more detail in theCompressor and/or Expander Device applications incorporated by referenceabove.

The gas inlet/outlet 228 can be coupled to, and in fluid communicationwith, a source of gas 234, such as, for example, a source of ambientair. The gas inlet/outlet 228 can also be coupled to, and in fluidcommunication with, a compressed gas storage structure 236 to which thecompressed gas can be transferred. Valves 244 can be used to alternatelyopen and close the fluid communication between the working chamber 242and the source of gas 234 and the working chamber 242 and the storagestructure 236. The liquid inlet/outlet 230 can be coupled to theactuator 222 and can be opened and closed via an optional valve 244 tocommunicate a volume of liquid to and from the working chamber 242 ofthe pressure vessel 220. The liquid outlet 232 can be coupled to, and influid communication with, the liquid purge system 238 and opened toevacuate a volume of the liquid from the working chamber 242 asdescribed in more detail below.

The actuator 222 can be configured the same as, or similar to, actuator122 described above. The actuator 222 includes a piston 252 disposedwithin a housing 254 that can be actuated to move liquid between thehousing 254 and the working chamber 242 via the liquid inlet/outlet 230.The piston 252 can be coupled to, for example, an electricmotor/generator or a hydraulically driven actuator, configured toactuate the piston 252.

The liquid purge system 238 includes a pump 246 coupled to, and in fluidcommunication with, the liquid outlet 232, and a first conduit 248coupled to, and in fluid communication with, a thermal managementfacility 240. The liquid purge system 238 also includes a second conduit250 coupled to, and in fluid communication with, the pump 246 and theactuator 222. The pump 246 can be actuated to move liquid from theworking chamber 242 to the thermal management facility 240. The pump 246can also be actuated to pump liquid from the thermal management facility240 to the actuator 222. As described above, the thermal managementfacility 240 can be, for example, a cooling tower or a settling pond,where heated liquid removed from the working chamber 242 can be cooledto a desired temperature. The cooled liquid can be cycled back into theactuator 222 and used again in a compression process as described inmore detail below.

In one example use, a first quantity of gas having a first pressure canbe introduced into the working chamber 242 in the direction of arrow A(shown in FIG. 2) via the gas inlet/outlet 228. For example, the valves244 coupled to the gas inlet/outlet 228 can be actuated to allow aquantity of gas from the source of gas 234 to be introduced into theworking chamber 242 of the pressure vessel 220. With the first volume ofgas disposed within the pressure vessel 220, the valves 244 coupled tothe gas inlet/outlet 228 can be closed and optionally, a valve 244coupled to the liquid inlet/outlet 230 can be opened. The actuator 222can then pump a volume of liquid (e.g., water) into the working chamber242 via the liquid inlet/outlet 230 in the direction of arrow B shown inFIG. 3. The volume of liquid can be pumped into the working chamber 242such that it compresses the gas within the working chamber 242. As thevolume of liquid compresses the gas within the working chamber 242, thecompressed gas, now at a second pressure greater than the firstpressure, can exit the working chamber 242 via the gas inlet/outlet 228and be transferred to the storage structure 236 as shown by arrow C inFIG. 3. For example, valves 244 coupled to the gas inlet/outlet 228 canbe actuated to allow the compressed gas to be moved from the workingchamber 242 to the storage structure 236.

At the end of the compression cycle, a valve 244 coupled to the liquidoutlet 232 can be opened to allow a volume of liquid 256 to be evacuatedfrom the working chamber 242 as shown by arrow D in FIG. 4. As describedabove, at least some of the heat energy from the compression process canbe transferred from the gas to the liquid. The evacuated volume ofliquid 256 can then be transferred to the thermal management facility240 via the liquid purge system 238. For example, the volume of liquid256 can be pumped through the liquid outlet 232 and then pumped throughthe conduit 248 and into the thermal management facility 240. Theremaining portion or volume of liquid 258 within the working chamber 242can be moved back into the actuator 222 in the direction of arrow E viathe liquid inlet/outlet 230, as shown in FIG. 5. Cooled liquid from thethermal management facility 240 can be transferred back to the actuator222 to replace the volume of liquid 256 that has been evacuated as shownby arrow F in FIG. 6. The above process can then be repeated tocontinuously compress gas.

In some embodiments, the cooled liquid can be transferred from thethermal management facility 240 to the actuator 222 after the remainingliquid 258 in the working chamber 242 is moved back into the actuator222. In some embodiments, the cooled liquid can be transferred from thethermal management facility 240 to the actuator 222 simultaneously withthe remaining liquid 258 in the working chamber 242 being moved backinto the actuator 222. In some embodiments, the cooled liquid can betransferred from the thermal management facility 240 directly back tothe working chamber 242.

In some embodiments, as the process is repeated, a quantity of gas canbe introduced into the working chamber 242 as shown by arrow G in FIG. 6simultaneously with the cooled liquid being transferred into theactuator 222. In some embodiments, a quantity of gas can be introducedinto the working chamber 242 simultaneously with the remaining liquid258 in the working chamber 242 being moved back into the actuator 222.In some embodiments, a quantity of gas can be introduced into theworking chamber 242 after the remaining liquid 258 in the workingchamber 242 has been moved back into the actuator 222. In someembodiments, a quantity of gas can be introduced into the workingchamber 242 simultaneously with the remaining liquid 258 in the workingchamber 242 being moved back into the actuator 222 and simultaneouslywith the cooled liquid being transferred into the actuator 222.

In the above example, an unspecified volume of liquid 256 was evacuatedfrom the pressure vessel 220. It should be understood that variousvolumes of liquid can be evacuated. For example, in some embodiments,5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%,75%, 80%, 85%, 90%, 95% or 100% of the liquid used to compress the gascan be evacuated from the working chamber 242 with the liquid purgesystem 238.

FIG. 7 illustrates another embodiment of a compression/expansion device.A compression/expansion device 300 includes a pressure vessel 320, anactuator 322 coupled to the pressure vessel 320, and a liquid purgesystem 338 coupled to a working chamber 342 of the pressure vessel 320and the actuator 322. The compression/expansion device 300 can be used,for example, to compress a gas, such as air, within the working chamber342 and/or to pressurize and/or pump a liquid, such as water. Thecompression/expansion device 300 can also be used in a compression andexpansion system such as a compressed air energy storage system and/orother suitable applications as described above.

The compression/expansion device 300 includes a gas inlet 329, a gasoutlet 328, and a liquid inlet/outlet 330, each coupled to the pressurevessel 320 and in fluid communication with working chamber 342 of thepressure vessel 320. The pressure vessel 320 can contain within theinterior region 342 at various time periods during a compression and/orexpansion cycle, a fluid, such as a liquid (e.g., water) and/or a gas(e.g., air). As described above for compression/expansion device 200,the compression/expansion device 300 can also include multiple valves344 each coupled to one of the gas inlet 329, the gas outlet 328, theliquid inlet/outlet 330, and/or to the pressure vessel 320. The valves344 can be configured to operatively open and close the fluidcommunication to and from the pressure vessel 320.

The gas inlet 329 can be coupled to, and in fluid communication with, asource of gas (not shown), such as, for example, a source of ambientair. The gas outlet 328 can be configured to communicate gas from theworking chamber 342 to another location, such as, for example, acompressed gas storage structure (not shown). The liquid inlet/outlet330 can be coupled to the actuator 322 and can be opened and closed viaa valve 344 to communicate liquid to and from the working chamber 342 tothe actuator 322.

The compression/expansion device 300 also includes a liquid outlet 332coupled to, and in fluid communication with, the liquid purge system 338and the working chamber 342. The liquid outlet 332 can be opened toevacuate a volume of the liquid from working chamber 342 as describedabove for compression/expansion device 200.

The actuator 322 can be configured the same as, or similar to, actuator122 and/or actuator 222 described above. The actuator 322 includes apiston 352 disposed within a housing 354 that can be actuated to moveliquid between the housing 354 and the working chamber 342 via theliquid inlet/outlet 330. The piston 352 can be coupled to, for example,an electric motor configured to actuate the piston 352.

The liquid purge system 338 includes a pump (not shown) coupled to, andin fluid communication with, the liquid outlet 332, and a first conduit348 coupled to, and in fluid communication with, a thermal managementfacility 340. The pump can be actuated to move liquid from the workingchamber 342 to the thermal management facility 340. The thermalmanagement facility 340 can include a pump (not shown) configured topump cooled liquid to the actuator 322 via a conduit 350.

In this embodiment, the compression/expansion device 300 includes a heattransfer element 324 in the form of multiple elongate members 360arranged in a bundle and extending vertically within the working chamber342. The elongate members 360 can be coupled together with a strap orband (not shown) that is coupled to the wall of the pressure vessel 320with a suitable coupling mechanism (not shown), such as, for example, abracket or clamp bolted to the wall of the pressure vessel 320. Theelongate members 360 can be solid or tubular (e.g., define a lumen). Asliquid flows into the working chamber 342, the liquid can flow betweenthe elongate members 360 and compress the gas (e.g., air) disposedwithin the working chamber 342. Heat energy can be transferred to theliquid and/or to the elongate members 360 of the heat transfer element324.

The compression/expansion device 300 can be used in the same or similarmanner as described above for compression/expansion device 200. In oneexample use, a first quantity of gas having a first pressure can beintroduced into the working chamber via the gas inlet 329. With thefirst quantity of gas disposed within the working chamber 342, theactuator 322 can then pump a volume of liquid (e.g., water) into theworking chamber 342 via the liquid inlet/outlet 330 such that the liquidcompresses the gas within the working chamber 342. As the volume ofliquid compresses the gas, the compressed gas, now at a second pressuregreater than the first pressure, can exit the working chamber 342 viathe gas outlet 328 and be transferred to a desired location. As theliquid flows within the pressure vessel 320 the liquid can flow betweenthe elongate members 360 such that at least some of the heat generatedduring compression can be transferred to the elongate members 360. Asdescribed above, at least some of the heat energy generated can betransferred from the gas to the liquid.

With the elongate members 360 disposed within the working chamber 342,the liquid is effectively separated into relatively long, narrowcolumns, which reduces the amount of vertical mixing of the liquid. Thisleads to vertical stratification of the liquid columns. The resultingtemperature at a top layer portion of the liquid, i.e., closest to thegas/liquid interface where heat energy is transferred from the gas tothe liquid, will be greater than other portions of the liquid that arefurther away from the gas/liquid interface. When the compression cycleis complete, this higher temperature layer or volume of liquid can thenbe evacuated from the working chamber 342 with the liquid purge system338, as described above for previous embodiments.

Specifically, at the end of the compression cycle, a volume of liquid356 can be evacuated from the working chamber 342 and transferred to thethermal management facility 340 via the liquid purge system 338. Theremaining portion or volume of liquid 358 within the working chamber 342can be moved back into the actuator 322 via the liquid inlet/outlet 330.Cooled liquid from the thermal management facility 340 can betransferred to the actuator 322 to replace the volume of liquid 356 thathas been evacuated. The above process can then be repeated.

The amount of heat energy removed from the working chamber 342 can thusbe controlled by the amount of liquid removed, and by the locationwithin the working chamber 342 from which the liquid is removed. Forexample, if there is relatively little vertical mixing of the liquid,the heat energy transferred from the gas to the liquid can be relativelyconcentrated near the gas/liquid interface, and a relatively largeportion of the total transferred heat energy can be removed from theworking chamber 342 by removing a relatively small portion of theliquid.

FIG. 8 schematically illustrates a portion of a compressor/expanderdevice according to another embodiment. A compressor/expander device 400can include one or more pressure vessels (cylinders) 420 having a firstworking chamber 462 and a second working chamber 464, an actuator 421connected to a piston 466 via a piston rod 427, and first heat transferelement 423 and a second heat transfer element 425 disposed within thepressure vessel 420. The compression/expansion device 400 can be used inthe same or similar manner as described above for previous embodiments,to compress and/or expand a gas (e.g., air). In this embodiment, thepiston 466 is used to move a liquid within the pressure vessel 420 tocompress and/or expand a gas within the pressure vessel 420.

More specifically, the first heat transfer element 423 is disposedwithin the first working chamber 462 and the second heat transferelement 425 is disposed within the second working chamber 464. Thecompressor/expander device 400 can be used, for example, to compressand/or expand a gas, such as air, within the first working chamber 462or the second working chamber 464. The compressor/expander device 400can be used, for example, in a CAES system. The pressure vessel 420 caninclude an inlet conduit 428 and an outlet conduit 429 in fluidcommunication with the first working chamber 462 and an inlet conduit430 and an outlet conduit 431 in fluid communication with the secondworking chamber 464. The first working chamber 462 and the secondworking chamber 464 can contain, at various time periods during acompression and/or expansion cycle, a quantity of the gas (e.g., air)and a quantity of the liquid (e.g., water) that can be communicated toand from the working chambers via the inlet/outlet conduits. Optionally,the pressure vessel 420 can include one or more additional conduits influid communication with the first working chamber 462 or the secondworking chamber 464 specifically dedicated to communicating gas orliquid to or from the first and second working chambers 462, 464. Thecompressor/expander device 400 can also include multiple valves (notshown in FIG. 8) coupled to the inlet/outlet conduits 428, 429, 430, and431 and/or to the pressure vessel 420. The valves can be configured tooperatively open and close the fluid communication to and from theworking chambers 462 and 464. Examples of use of such valves aredescribed in more detail in the Compressor and/or Expander Deviceapplications incorporated by reference above.

The actuator 465 can be any suitable mechanism for causing reciprocalmovement of the piston 466 within the pressure vessel 420. As the piston466 is moved back and forth within the pressure vessel 420, the volumeof the first working chamber 462 and the second working chamber 464and/or the portion of the volume of the first working chamber 462 andthe second working chamber 464 that can be occupied by gas can beselectively changed. The actuator 465 can be for example, an electricmotor or a hydraulically driven actuator such as, for example, thehydraulic actuators described in the Ingersoll I applicationincorporated herein by reference above. The actuator 465 can be coupledto the piston 466 via the piston rod 427 and used to move the piston 466back and forth within the interior region of the pressure vessel 420.For example, the working chamber 462 can be defined by the cylinder 420and the bottom face of piston 466. Similarly, the working chamber 464can be defined by the cylinder 420 and the top face of the piston 466.In this manner, the piston 466 is movably disposed within the interiorregion of the cylinder 420 and can divide the interior region between afirst interior region (working chamber 462) and a second interior region(working chamber 464).

As the piston 466 moves back and forth within the interior region of thecylinder 420, a volume of the first working chamber 462 and a volume ofthe second working chamber 464 will each change. For example, the piston466 can be moved between a first position (e.g., top dead center) inwhich the first working chamber 462 includes a volume of fluid greaterthan a volume of fluid in the second working chamber 464, and a secondposition (e.g., bottom dead center) in which the second working chamber464 includes a volume of fluid greater than a volume of fluid in thefirst working chamber 462. As used herein, “fluid” means a liquid, gas,vapor, suspension, aerosol, or any combination of thereof. At least oneseal member (not shown), such as, for example, a rolling seal member canbe disposed within the first working chamber 462 and the second workingchamber 464 of the cylinder 420 and can be attached to the piston 466.The arrangement of the rolling seal member(s) can fluidically seal thefirst working chamber 462 and the second working chamber 464 as thepiston 466 moves between the first position (i.e., top dead center) andthe second position (i.e., bottom dead center). Examples and use of arolling seal member are described in more detail in the Ingersoll IIIapplication incorporated by reference above.

In some embodiments, the piston 466 is moved within the pressure vessel420 to compress a gas, such as air, within the pressure vessel 420. Insome embodiments, the piston 466 can be configured to be single-acting(e.g., actuated in a single direction to compress and/or expand gas). Asshown in FIG. 8, the compressor/expander device 400 is configured to bedouble-acting in that the piston 466 can be actuated in two directions.In other words, the piston 466 can be actuated to compress and/or expandgas (e.g., air) in two directions. For example, in some embodiments, asthe piston 466 is moved in a first direction, a first volume of a fluid(e.g., water, air, and/or any combination thereof) having a firstpressure can enter the first working chamber 462 of the cylinder 420 onthe bottom side of the piston 466. In addition, a second volume of thefluid having a second pressure can be compressed by the top side of thepiston 466 in the second working chamber 464. The gas portion of thesecond volume of fluid can then exit the second working chamber 464.When the piston 466 is moved in a second direction opposite the firstdirection, the gas portion of the first volume of fluid within the firstworking chamber 462 can be compressed by the piston 466. The gas portionof the first volume of fluid can then exit the first working chamber 462having a third pressure greater than the first pressure, andsimultaneously a third volume of fluid can enter the second workingchamber 464.

The heat transfer element 423 disposed within the first working chamber462 and the heat transfer element 425 disposed within the second workingchamber 464 can be a variety of different configurations, shapes, sizes,structures, etc. to provide a relatively high surface area per unitvolume or mass that can be in contact with the gas (e.g., air) as it isbeing compressed or expanded. In this embodiment, as shown in FIG. 8,the heat transfer element 423 is disposed near the bottom surface of thepiston 466 and the heat transfer element 425 is disposed at a topportion of the second working chamber 464. In some embodiments, the heattransfer element 423 disposed within the first working chamber 462 canbe attached to the bottom face of the piston 466. Similarly, in someembodiments, the heat transfer element 425 disposed within the secondworking chamber 464 can be attached to the top face of the piston 466,as described in further detail herein. In such embodiments, the heattransfer elements 423, 425 can move with the piston 466 as it isactuated.

In some embodiments, it may be desirable to form the heat transferelements 424 with a material that can provide high thermal conductivity.For example, the heat transfer elements 424 (i.e., the heat transferelement 423 and the heat transfer element 424) can be formed with metals(e.g. stainless steel) in the form of, for example, sheet or wire,carbon fiber, nano-materials, and hybrid or composite materials (e.g.carbon polymer compounds) which have anti-corrosion properties, arelighter weight, and are less expensive than some metallic materials. Theheat transfer elements 424 can be, for example, substantially similar tothe heat transfer element 324 described with respect to FIG. 7.

The compressor/expander device 400 also includes an actuator 421 and anactuator 422 that can each be configured the same as, or similar to,actuator 122 and/or actuator 222 described above. The actuators 421 and422 can each include a piston (not shown) disposed within a housing (notshown). The actuator 422 can be actuated to move liquid between thehousing and the first working chamber 462 via a liquid inlet/outlet 433,and the actuator 421 can be actuated to move liquid between the housingand the second working chamber 464 via a liquid inlet/outlet 435. Thepistons of the actuators 421 and 422 can each be coupled to, forexample, an electric motor or hydraulic actuator configured to actuatethe pistons.

The compression/expansion device 400 can also include a first liquidoutlet 468 coupled to, and in fluid communication with, a liquid purgesystem 438 and the first working chamber 462, and a second liquid outlet470 coupled to, and in fluid communication with, the liquid purge system438 and the second working chamber 464. The liquid purge system 438 canbe configured the same as or similar to, and function the same as orsimilar to, the liquid purge systems 238 and 338 described above. Thefirst liquid outlet 468 can be opened to evacuate a volume of the liquidfrom the first working chamber 462, and the second liquid outlet 470 canbe opened to evacuate a volume of the liquid from the second workingchamber 464, as described above for previous embodiments.

The liquid purge system 438 can include a first pump (not shown) coupledto, and in fluid communication with, the first liquid outlet 468, and afirst conduit (not shown) coupled to, and in fluid communication with, athermal management facility (not shown). The liquid purge system 438 canalso include a second pump (not shown) coupled to, and in fluidcommunication with, the second liquid outlet 470, and a second conduit(not shown) coupled to, and in fluid communication with, the thermalmanagement facility. The pumps can each be actuated to move liquid fromthe first working chamber 462 and the second working chamber 464 to thethermal management facility. The thermal management facility can includea pump (not shown) configured to pump cooled liquid to the actuator 421and 422. In some embodiments, the liquid purge system 438 and actuators421 and 422 can be subsystems of a liquid management system thatincludes a thermal management facility.

In use, when the piston 466 is actuated to compress a gas within thepressure vessel 420, the liquid purge system 438 can be used to removeheat generated during the compression process. For example, when thepiston 466 is actuated to compress a gas within the second workingchamber 464, heat generated during compression can be transferred to theheat transfer element 425 and then from the heat transfer element 425and by pumping a volume of liquid into the second working chamber 464using the actuator 421. The liquid pumped into the second workingchamber 4 t 64 can also contribute to the compression of the gas asdescribed above for previous embodiments. During the compressionprocess, the resulting temperature at a top layer portion of the liquid,i.e., closest to the gas/liquid interface where heat energy istransferred from the gas to the liquid, will be greater than otherportions of the liquid that are further away from the gas/liquidinterface. When the compression cycle is complete (e.g., when the piston466 reaches the end of its stroke at a top portion of the second workingchamber 464) this higher temperature layer or volume of liquid can thenbe evacuated from the second working chamber 464 via the conduit 470with the liquid purge system 438, as described above for previousembodiments.

Specifically, at the end of the compression cycle, a volume of liquidcan be evacuated from the second working chamber 464 and transferred tothe thermal management facility via the liquid purge system 438. Theremaining portion or volume of liquid within the second working chamber464 can be moved back into the actuator 421 via the liquid inlet/outlet435. Cooled liquid from the thermal management facility can betransferred to the actuator 421 to replace the volume of liquid that hasbeen evacuated. The same process occurs when the piston 466 is moved inthe opposite direction to compress gas within the first working chamber462.

The amount of heat energy removed from the working chambers 462 and 464can thus be controlled by the amount of liquid removed, and by thelocation within the working chambers 462, 464 from which the liquid isremoved. For example, if there is relatively little vertical mixing ofthe liquid, the heat energy transferred from the gas to the liquid canbe relatively concentrated near the gas/liquid interface, and arelatively large portion of the total transferred heat energy can beremoved from the working chambers 462, 464 by removing a relativelysmall portion of the liquid.

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. Where methods and steps described aboveindicate certain events occurring in certain order, those of ordinaryskill in the art having the benefit of this disclosure would recognizethat the ordering of certain steps may be modified and that suchmodifications are in accordance with the variations of the invention.Additionally, certain of the steps may be performed concurrently in aparallel process when possible, as well as performed sequentially asdescribed above. The embodiments have been particularly shown anddescribed, but it will be understood that various changes in form anddetails may be made.

For example, although various embodiments have been described as havingparticular features and/or combinations of components, other embodimentsare possible having any combination or sub-combination of any featuresand/or components from any of the embodiments described herein.Additionally, the specific configurations of the various components of acompression/expansion device can also be varied. For example, the sizeand specific shape of the various components can be different than theembodiments shown, while still providing the functions as describedherein.

Although not shown, the compression/expansion device 200 can optionallyinclude a heat transfer element disposed within the working chamber 242of the pressure vessel 220 as described above for compression/expansiondevice 100 and compression/expansion device 300. In such an embodiment,heat energy from a compression process can be transferred to the heattransfer element and to the liquid used to compress the gas.

As previously described, in some embodiments, a compression and/orexpansion device as described herein can be used within a multi-stageair compression/expansion system. In some such embodiments, a liquidpurge system can be used to evacuate a volume or portion of liquid fromone stage of the multi-stage compression/expansion system, and transferthe evacuated liquid to thermal management facility as described above.In some embodiments, a liquid purge system can be used to evacuate avolume or portion of liquid from one stage of the multi-stagecompression/expansion system, and transfer the evacuated liquid toanother stage of the system.

1. An apparatus suitable for use in a compressed gas-based energystorage and recovery system, the apparatus comprising: a pressure vesselhaving a working piston disposed therein for reciprocating movement inthe pressure vessel, the working piston defining at least in partbetween a first side thereof and the pressure vessel a working chamberconfigured to contain at least one of a liquid or a gas; a firsthydraulic actuator fluidically coupleable to the working chamber of thepressure vessel a second hydraulic actuator coupled to the workingpiston; a hydraulic controller operable to cause the first actuator tomove a volume of liquid contained therein to the working chamber of thepressure vessel, and to cause the second actuator to move the workingpiston to reduce the volume of working chamber, so that: a quantity ofgas contained therein can be compressed and the quantity of compressedgas can be discharged out of the working chamber, and heat energyproduced by the compression of the quantity of gas can be transferredfrom the quantity of gas to the volume of liquid, thereby raising thetemperature of a first portion of the volume of liquid from a firsttemperature at which it is moved into the working chamber to a secondtemperature greater than the first temperature and raising thetemperature of a second portion of the liquid to a third temperaturegreater than the second temperature, and the hydraulic controllerfurther operable to move the working piston: a) a first distance suchthat the quantity of gas contained in the working chamber can bedischarged from the working chamber, and b) a second distance such thatthe second portion of the liquid having a third temperature can bedischarged from the working chamber.
 2. The apparatus of claim 1,further comprising: a purge system fluidically coupleable to thepressure vessel, the purge system configured to receive the secondportion of the liquid from the working chamber.
 3. The apparatus ofclaim 1, further comprising: a purge system fluidically coupleable tothe first hydraulic actuator, the purge system configured to supply avolume of liquid to the actuator having a fourth temperature, the fourthtemperature being less than the third temperature.
 4. The apparatus ofclaim 1, further comprising: a purge system fluidically coupled to athermal management system, the purge system configured to transferliquid removed from the pressure vessel to the thermal managementsystem.
 5. The apparatus of claim 1, further comprising: a heat transferelement disposed within the working chamber of the pressure vessel, theheat transfer element configured to receive heat energy from the gasbeing compressed to reduce the temperature of the compressed gas.
 6. Theapparatus of claim 5, wherein the heat transfer element is configured totransfer heat energy received from the compressed gas to the exterior ofthe working chamber.
 7. The apparatus of claim 5, wherein the heattransfer element is configured to transfer heat energy received from thecompressed gas to the liquid contained in the working chamber.
 8. Theapparatus of claim 1, further comprising: a plurality of elongate heattransfer elements disposed within the interior region of the pressurevessel, the plurality of elongate heat transfer elements configured toreceive heat energy from the gas being compressed in the working chamberof the pressure vessel and to enhance thermal stratification of thevolume of liquid.
 9. The apparatus of claim 1, wherein the workingchamber is a first working chamber, the working piston defining at leastin part between a second side thereof and the pressure vessel a secondworking chamber configured to contain at least one of a liquid or a gas.10. A method of compressing gas in a compressed gas-based energy storageand recovery system using a pressure vessel, the pressure vesseldefining an interior region in which at least one of a liquid or a gascan be contained, the method comprising: moving a volume of liquid intothe interior region of the pressure vessel such that a portion of thevolume of liquid contacts a portion of a quantity of gas disposed withinthe interior region of the pressure vessel and compresses the quantityof gas, the volume of gas having a first pressure prior to beingcompressed; removing the quantity of gas from the interior region of thepressure vessel, the quantity of gas being removed having a secondpressure greater than the first pressure, the volume of liquid having afirst portion having a first temperature and a second portion having asecond temperature greater than the first temperature after the volumegas has been compressed; and removing from the interior region of thepressure vessel the second portion of the volume of liquid.
 11. Themethod of claim 10, further comprising: removing from the pressurevessel the first portion of the volume of liquid.
 12. The method ofclaim 10, wherein the volume of liquid is received from a hydraulicactuator fluidically coupleable to the pressure vessel, the methodfurther comprising: transferring the first portion of the volume ofliquid from the pressure vessel to the hydraulic actuator.
 13. Themethod of claim 10, further comprising: transferring the second portionof the volume of liquid to a thermal management system.
 14. A method ofcompressing gas in a compressed gas-based energy storage and recoverysystem using pressure vessel, the pressure vessel defining an interiorregion in which at least one of a liquid or a gas can be contained, thepressure vessel having a piston disposed therein for reciprocatingmovement in the pressure vessel and dividing the interior region of thepressure vessel into, and defining therewith, a first working chamberand a second working chamber, the method comprising: moving a volume ofliquid into the first working chamber of the pressure vessel such that aportion of the volume of liquid contacts a portion of a quantity of gasdisposed within the first working chamber of the pressure vessel; movingthe piston within the pressure vessel from a first position in which avolume of the first working chamber is greater than a volume of thesecond working chamber to a second position in which the volume of thefirst working chamber is less than the volume of the second workingchamber, the piston and the volume of liquid collectively configured tocompress the quantity of gas when the piston is moved from its firstposition to its second position; substantially simultaneously with themoving the piston, moving the compressed gas from the first workingchamber; and removing from the first working chamber of the pressurevessel a portion of the volume of liquid, the removed portion of thevolume of liquid being a first portion of the volume of liquid andhaving a first temperature, the volume of liquid having a second portionhaving a second temperature, the first temperature being greater thanthe second temperature.
 15. The method of claim 14, further comprising:removing from the first working chamber of the pressure vessel thesecond portion of the volume of liquid.
 16. The method of claim 14,wherein the volume of liquid is received from a hydraulic actuatorcoupled to the pressure vessel, the method further comprising:transferring the second portion of the volume of liquid from the firstworking chamber of the pressure vessel to the hydraulic actuator. 17.The method of claim 14, wherein the quantity of gas is a first quantityof gas, and further comprising: moving the piston within the pressurevessel from its second position to its first position such that a secondquantity of gas within the second working chamber is compressed by thepiston.
 18. The method of claim 14, wherein the quantity of gas is afirst quantity of gas, and further comprising: moving the piston withinthe pressure vessel from its second position to its first position suchthat a second quantity of gas within the second working chamber iscompressed by the piston; and substantially simultaneously with themoving the piston from its second position to its first position, movingthe compressed gas from the second working chamber.
 19. The method ofclaim 14, further comprising: moving a volume of liquid into the secondworking chamber of the pressure vessel such that a portion of the volumeof liquid in the second working chamber contacts a portion of a quantityof gas disposed within the second working chamber; moving the pistonwithin the pressure vessel from its second position to its firstposition such that the quantity of gas within the second working chamberis compressed by the piston; substantially simultaneously with themoving the piston from its second position to its first position, movingthe compressed gas from the second working chamber; removing from thesecond working chamber a portion of the volume of liquid, the removedportion of the volume of liquid being a first portion of the volume ofliquid in the second working chamber and having a third temperature, thevolume of liquid within the second working chamber having a secondportion having a fourth temperature, the third temperature being greaterthan the fourth temperature.
 20. The method of claim 14, furthercomprising: transferring the first portion of the volume of liquid to athermal management system.